A primary function of a roof covering is to prevent rain, snow, sleet, etc. from entering into the dwelling or structure. Many types of roof coverings have been developed, including tile, stone, cement, metal, wood shingles, composition asphalt shingles, all of which shelter the dwelling from the weather elements. In the construction of residential homes, the standard wood shingle and the “shake” shingle have become very popular, due primarily to the aesthetic appearance. The wood shingle, and especially the shake type of shingle is thicker than a conventional composition asphalt shingle, thereby providing a highly contoured surface which presents an aesthetically pleasing “rough” or rustic appearance characterized by juxtaposed light and dark areas or shadows. However, such a wood product type of shingle is expensive, has a limited life, and is prone to severe damage or destruction due to hail, fire, and the like. Despite these disadvantages, the wood shingles remain a very popular roof covering for residential homes.
A majority of residential homes are constructed with a composition-asphalt type of shingle because of the lower cost and long life thereof. In addition, the asphalt type of shingle is more easily installed than the wood shingle, and can be selected from a large variety of colors so that the roof of one residential home does not look the same as the neighboring structure. Improvements continue to be made in the asphalt shingle industry to simulate the appearance or texture characteristics of wood shingles. To that end, the ceramic or mineral granules are often chosen to simulate the color of either a new or weathered cedar wood shingle. Further, asphalt shingles have been constructed in an attempt to simulate the shadow effect of wood shingles by utilizing a darker color ceramic granule at specific areas on the shingle. See, for example, U.S. Pat. No. 5,369,929 by Weaver et al. which is a two-ply shingle with three horizontal color striations to provide a color gradient. The lighter color striation is at the leading edge of the shingle, whereas the darker color striation is at the upper portion of the weather surface part of the shingle. Each striation can also be of a different color to provide different visual effects.
While single layer asphalt shingles could themselves be constructed with a greater thickness to simulate the rustic or rough wood surface with shadowed areas, the weight of the shingle may then be in excess of that required by industry standards, the shingle would be more difficult to install, and would be more costly. As an alternative, asphalt shingles have been developed as a two-ply laminate structure. U.S. Pat. Nos. 5,369,929 and 5,195,290 both disclose a two-ply asphalt type of shingle. One purpose of the two-ply asphalt shingle, together with color variations and shading, is to more closely simulate the wood-type shingle. In U.S. Pat. No. 5,195,290, each ply of the two-ply asphalt shingle appears to be the same width, which is the shorter dimension of the shingle. As such, each shingle requires substantial material and is correspondingly heavy. The shingle disclosed in U.S. Pat. No. 5,369,929 is constructed with a full size upper ply and a lower ply that is approximately half the width of the upper ply. The partial-width lower ply reduces the weight of the shingle. A lower ply width of approximately half the upper ply width or less facilitates packaging of the shingles in a stack with the overhanging portion of the full width upper plies interleaved to form a bundle that does not crown (i.e., rise up) in the center. However, such multiple-ply asphalt singles with partial-width lower plies have a feature, termed the nail zone, which is that portion of the upper-most ply which directly overlies some portion of all the lower plies but which is not exposed to the weather when a subsequent row or course of shingles is installed on the roof. Nails must be installed in the nail zone in order to anchor all plies of the shingle to the roof without being susceptible to leakage (i.e., because they are covered by the subsequent course of shingles).
On conventional multiple-ply shingles with partial-width lower plies approximately half the upper ply width, the nail zone is a horizontal stip approximately 1-inch wide centered approximately 5½ inches to 6 inches from the butt edge of the shingle. The useable width of the nail zone is smaller, however, typically ½ inch to ⅞ inch, to avoid showing the head of the roofing nail after the next course is installed. The location and size of the nail zone is not a matter of choice, but rather is dictated by the structure of the shingle and the amount of each shingle (typically 5 inches or 5½ inches) left exposed to the weather after subsequent courses of shingles are installed according to industry or local practice. Thus, in shingles having a lower ply width approximately half the upper ply width, such as disclosed in U.S. Pat. No. 5,369,929, the nail zone is inherently small. With a small nail zone, there is an increased likelihood that some shingles will be incorrectly installed during nailing to the roof structure. This can lead to leaking, decreased wind resistance, or other problems.
In U.S. Pat. No. 5,195,290, by Hulett, a three-ply shingle is shown constructed substantially identical to the two-ply shingle also disclosed therein. In other words, each of the three plies of the shingle is constructed with the same width, and adhered to each other to form a composite three-ply shingle. As such, the individual shingles are heavy and if packed in a standard sized bundle, such bundle is expected to exceed the standard and accepted weight of a bundle of asphalt shingles. U.S. Pat. No. 4,869,942 by Jennus et al. discloses a trilaminated roofing shingle to provide a physically thick shingle structure at the butt edge, but with only a top layer and bottom layer thereof providing weather-exposed surfaces. In that the second layer of the disclosed trilaminated roofing shingle has no weather-exposed surface, there are a reduced number of granule color variations that can be embedded into such surfaces.
Conventional asphalt shingles, whether of the single or double ply, often suffer the disadvantage of visual defects when installed on a roof. For example, certain roofs will appear to have a “zippered” effect, due to the regularly repeating type or color of the shingle as well as the manner in which the shingles are installed. Other multiple-color shingles will produce a “blotchy” color effect when installed, due primarily to the lack of different color patterns by which the shingles are constructed. Both of these effects are natural artifacts of the design and manufacturing techniques of the shingles, and are due to the lack of a randomness of the few visual features available. In other words, if a shingle design has only a few features, such a tab size or tab color, then it is difficult to obtain a uniform degree of randomness between shingles when installed on a roof. It is also appreciated that it is not an easy task to develop machines and shingle production facilities that provide each shingle with randomized features. In contrast, machines are more easily designed that produce shingles, each with identical features.
The wood-type shingles inherently have randomized features, especially as to color and texture, as trees grow in a nonuniform manner. The wood grain is different from the core to the outside of the tree, and the wood color of each tree is somewhat different. The randomness of features of wood shingles is enhanced by cutting the shingles of a bundle to many different sizes. While this facilitates a uniform randomness in the shingles, it substantially increases the time to install such type of shingle.
In view of the foregoing, there exists a need for a new type of three-ply asphalt shingle that does not exceed a standard and accepted weight, and that provides multiple weather-exposed surfaces on which different color combinations of granules can be deposited. Another need exists for a multiple layer asphalt shingle having an increased nail zone width, thereby resulting in fewer installation errors. Another need exists for a shingle having three layers, each with a weather-exposed surface, and each provided with different shades and/or color combinations of mineral granules. Another need exists for a multiple layer asphalt shingle having many different size and color features to thereby enhance a randomization of the features and provide an aesthetically pleasing roof.